alpine 3.9
race weakness #3

5

Weakness Breakdown


Definition:

A race condition exists when parallel code accesses shared data without proper coordination. An attack that uses a race-condition weakness takes advantage of the unsafe data access to manipulate how one of the parallel sections of code reacts. Even though each process runs as intended, the outcome is unexpected. For example, consider a bank service that depends on an encryption key that it reads from a known location. An independent cryptography service is responsible for generating the key and placing it where the bank is expected to read it in a timely manner. If the bank and cryptography services do not coordinate with each other, then the bank may read a blank encryption key before cryptography writes the key to the location. This can effectively turn off all encryption for the bank without either service, or the administrator, knowing that something has gone wrong.

Warning code(s):

This accepts filename arguments; if an attacker can move those files, a race condition results..

File Name:

dos2unix/src/dos2unix-7.4.0/common.c

Context:

The highlighted line of code below is the trigger point of this particular Alpine 3.9 race weakness.

          errstr = strerror(errno);
         D2U_UTF8_FPRINTF(stderr, "%s: ", progname);
         D2U_UTF8_FPRINTF(stderr, _("Failed to change the permissions of temporary output file %s:"), TempPath);
         D2U_ANSI_FPRINTF(stderr, " %s\n", errstr);
       }
    }
  }
#endif

#ifndef NO_CHOWN
  if (!RetVal && (ipFlag->NewFile == 0)) { /* old-file mode */
     /* Change owner and group of the temporary output file to the original file's uid and gid. */
     /* Required when a different user (e.g. root) has write permission on the original file. */
     /* Make sure that the original owner can still access the file. */
     if (chown(TempPath, StatBuf.st_uid, StatBuf.st_gid)) {
        if (ipFlag->AllowChown) {
          if (ipFlag->verbose) {
            D2U_UTF8_FPRINTF(stderr, "%s: ", progname);
            D2U_UTF8_FPRINTF(stderr, _("The user and/or group ownership of file %s is not preserved.\n"), ipOutFN);
          }
#ifndef NO_CHMOD
          /* Set read/write permissions same as in new file mode. */
          mask = umask(0); /* get process's umask */
          umask(mask); /* set umask back to original */
          RetVal = chmod(TempPath, StatBuf.st_mode & ~mask); /* set original permissions, minus umask */
          if (RetVal) {
             if (ipFlag->verbose) {
               ipFlag->error = errno;
               errstr = strerror(errno);
               D2U_UTF8_FPRINTF(stderr, "%s: ", progname);
               D2U_UTF8_FPRINTF(stderr, _("Failed to change the permissions of temporary output file %s:"), TempPath);
               D2U_ANSI_FPRINTF(stderr, " %s\n", errstr);
             }
          }
#endif
        } else {
          if (ipFlag->verbose) {
            ipFlag->error = errno;
            errstr = strerror(errno);
            D2U_UTF8_FPRINTF(stderr, "%s: ", progname);
            D2U_UTF8_FPRINTF(stderr, _("Failed to change the owner and group of temporary output file %s:"), TempPath);
            D2U_ANSI_FPRINTF(stderr, " %s\n", errstr);
          }
          RetVal = -1;
        }
     }
  }
#endif

  if ((!RetVal) && (ipFlag->KeepDate)) 

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